Gallium Containing Zinc Oxide

ABSTRACT

It is an object of the present invention to provide a gallium containing zinc oxide with an improved heat ray shielding function while keeping high transparency to visible light rays. The present invention is directed to a gallium containing zinc oxide, which has a heat ray shielding function, a gallium content of in the range of 0.25 to 25% by weight, and a carrier electron density n e  of 2×10 20 /cm 3  or higher.

TECHNICAL FIELD

The present invention relates to a gallium containing zinc oxide with animproved heat ray shielding function while keeping high transparency tovisible light rays.

BACKGROUND ART

Conventionally, different kind metal-doped conductive metal oxides suchas tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), andaluminum-doped zinc oxide (AZO) have been known as materials transparentof visible light rays and having high conductivity and they have beenused as transparent conductive films and transparent electrodes ofliquid crystal displays and solar cells. Further, glass on which theseconductive metal oxides are deposited has been used as heat rayshielding glass for windows of buildings and windows of automobiles.

Among these heat ray shielding materials, in particular, tin-dopedindium oxide (ITO) is excellent in the heat ray shielding function,however since indium reserve is slight and indium is a by-product ofminerals of zinc and lead, exhaustion and steep rise in costs because ofmass consumption for the transparent conductive films for liquid crystaldisplays in recent years have been serious concern.

As a heat ray shielding material in place of ITO having these resourcesproblem, and the supply and the cost problem, heat ray shieldingmaterials using zinc oxide whose raw materials exist in abundance andeconomical have been investigated. However, zinc oxide is inferior inthe shielding property of light rays with wavelength near infrared (IR)region as compared with ITO.

As heat ray shielding materials of different metal-doped zinc oxide,aluminum containing zinc oxide thin films are disclosed in PatentDocument No. 1 and No. 2. However, aluminum is easier to be reacted withoxygen than zinc, a component element of zinc oxide, and as a result, ina product such as a thin film, aluminum is locally precipitated in formof an oxide and causes a problem that the optical properties such astransmission and refractive index and electric properties such asconductivity are uneven. Further, aluminum element has another problemthat aluminum is not easy to be added (doped) by film formation methodsother than sputtering. Furthermore, it is also difficult to add aluminumto a concentration sufficient to exhibit the heat ray shieldingfunction.

Patent Document No. 3 discloses zinc oxide thin films containing atleast one kind of Group XIV elements.

In the sunrays, IR rays having wavelength of at shortest 780 nm longerthan visible light rays have a small energy quantity, about 10%, ascompared with ultraviolet (UV) rays, however IR rays have a significantthermal function and are released as heat energy to increase thetemperature if once being absorbed in a substance and therefore they aregenerally called as heat ray.

Accordingly, for example, if it is made possible to shield IR rayshaving the significant thermal function among sunrays coming through anaperture part, the heat shielding property is heightened and thetemperature increase in the inside can be suppressed. Particularly, theenergy ratio of near IR rays with wavelength of 780 to 1500 nm in IRrays is high and the energy ratio of near IR rays with wavelength of 780to 1000 nm is particularly high. As a matter of fact, with respect to aweighed coefficient for calculating the solar transmission Ts accordingto JIS R 3106, it is set higher. In other words, if the near IR rayswith wavelength of 780 to 1000 nm are not effectively shielded, thesolar transmission can not be lowered while the visible lighttransmission is kept high.

However, the zinc oxide thin films containing at least one kind of GroupXIV elements disclosed in Patent Document No. 3 have high transmission,about 90% of light rays with wavelength of 750 nm and about 80% of lightrays with wavelength of 1000 nm and thus are incapable of sufficientlysuppressing the solar transmission while keeping the visible lighttransmission high.

Patent Document No. 1: Japanese Kokai Publication Sho-61-96609

Patent Document No. 2: Japanese Kokai Publication Hei-1-201021

Patent Document No. 3: Japanese Patent No. 1802011

DISCLOSURE OF THE INVENTION Problems which the Invention is to Solve

In view of the above-mentioned state of the art, the present inventionaims to provide a gallium containing zinc oxide with an improved heatray shielding function while keeping high transparency to visible lightrays.

Means for Solving the Object

The present invention provides a gallium containing zinc oxide, whichhas a heat ray shielding function, a gallium content of in the range of0.25 to 25% by weight, and a carrier electron density n_(e) of2×10²⁰/cm³ or higher. Hereinafter, the present invention will bedescribed in detail.

On the basis of results of intensive investigations, inventors of thepresent invention have found that a gallium containing zinc oxideobtained by adding a gallium in a specified content to zinc oxide andcontrolling the carrier electron density to be a prescribed value canlower the transmission of light with wavelength in the near IR regionwhile keeping the visible light transmission high and the findings haveled to completion of the present invention.

Herein, a gallium containing zinc oxide obtained by adding a gallium ina specified content to zinc oxide is disclosed in Japanese Patent No.3453805, however the gallium containing zinc oxide in this patent isproduced to improve the conductivity.

On the other hand, the gallium containing zinc oxide of the presentinvention is based on the finding that there are correlations of theheat ray shielding function with the carrier electron density and thecarrier electrons mobility of the gallium containing zinc oxide.

Accordingly, a metal thin film having visible light transmission andsolar transmission in properly controlled ranges can be produced.

Additionally, with respect to the gallium containing zinc oxide of thepresent invention, as described below, the oxygen flow amount isadjusted at the time of production, so that the oxygen deficient degreecan be controlled and consequently, the carrier electron density and thecarrier electron mobility can be changed and gallium containing zincoxide having an excellent heat ray shielding function can be obtainedwithout considerable change of the crystal structure.

For that, the gallium containing zinc oxide described in Japanese PatentNo. 3453805 and the gallium containing zinc oxide of the presentinvention are totally different from each other.

The content of gallium in the gallium containing zinc oxide of thepresent invention is 0.25% by weight in the lower limit and 25% byweight in the upper limit for the entire gallium containing zinc oxide.If it is lower than 0.25% by weight, the transmission of light withwavelength in near IR region becomes high and the gallium containingzinc oxide does not have the heat ray shielding function and if itexceeds 25% by weight, gallium causes metal agglomeration or isconverted into oxide to form precipitates and it results in significantdispersion of local brightness and heat ray shielding property in aplane and impossibility of attaining high heat ray shielding function.The content is preferably 1% by weight in the lower limit and 15% byweight in the upper limit, more preferably 1.5% by weight in the lowerlimit and 11% by weight in the upper limit, furthermore preferably 3% byweight in the lower limit and 6% by weight in the upper limit, even morepreferably 4% by weight in the lower limit and 5.5% by weight in theupper limit, and mostly preferably 5% by weight in the upper limit.

The content of gallium in the gallium containing zinc oxide of thepresent invention can be calculated by XRF (X-Ray Fluorescenceanalysis)-FP (Fundamental Parameter) method beside the above-mentionedweight ratio and it is preferably 1×10²⁰/cm³ in the lower limit and80×10²⁰/cm³ in the upper limit.

The carrier electron density n_(e) of the gallium containing zinc oxideof the present invention is 2×10²⁰/cm³ in the lower limit. The heat rayshielding function of the gallium containing zinc oxide of the presentinvention is attributed to the electron movement between gallium andzinc oxide and if the carrier electron density is lower than 2×10²⁰/cm³,no sufficient heat ray shielding function can be obtained. The lowerlimit is preferably 7×10²⁰/cm³ and more preferably 1×10²¹/cm³.

The carrier electron mobility μ of the gallium containing zinc oxide ofthe present invention is not particularly limited, however it ispreferably 0.1 cm²/Vs in the lower limit and 40 cm²/Vs in the upperlimit. If it is lower than 0.1 cm²/Vs, owing to uneven precipitation ofimpurities in the zinc oxide crystal structure, plane distribution ofgallium concentration becomes wide and the structure becomes unstableand if it exceeds 40 cm²/Vs, the heat ray shielding function becomesinsufficient. It is more preferably 1 cm²/Vs in the lower limit and 35cm²/Vs in the upper limit, furthermore preferably 5 cm²/Vs in the lowerlimit and 32 cm²/Vs in the upper limit, and even more preferably 10cm²/Vs in the lower limit and 30 cm²/Vs in the upper limit.

With respect to the gallium containing zinc oxide of the presentinvention, the above-mentioned carrier electron density and the carrierelectron mobility can be obtained by measuring hole effect measurementby the method of L. J. van der Pauw and in the case of measurement forthe gallium containing zinc oxide of the present invention in form of athin film, they can be determined by at first measuring the filmthickness by a contact method or the like and then carrying out the holeeffect measurement by the method of L. J. van der Pauw.

With respect to the gallium containing zinc oxide of the presentinvention, it is preferable that the carrier electron density n_(e) andthe carrier electron mobility μsatisfy the following inequality:0.2≦(n_(e)×10⁻²⁰/μ) and the solar transmission Ts and the visible lighttransmission Tv satisfy the following inequality: Tv/Ts≧1.0. If thecarrier electron density n_(e) and the carrier electron mobility μ arecontrolled to satisfy the inequality: 0.2≦(n_(e)×10⁻²⁰/μ), the solartransmission Ts and the visible light transmission Tv are controlled tosatisfy the inequality: Tv/Ts≧1.0. From a viewpoint of practicalapplication, it is preferably 0.2≦(n_(e)×10⁻²⁰/μ)≦50, more preferably0.2≦(n_(e)×10⁻²⁰/μ)≦20, furthermore preferably 0.2≦(n_(e)×10⁻²⁰/μ)≦10,and even more preferably 0.2≦(n_(e)×10⁻²⁰/μ)≦5.

Generally, to improve the conductivity of zinc oxide, it is tried toobtain high conductivity by increasing the carrier electron density aswell as the carrier electron mobility.

Accordingly, it is desired for conductive zinc oxide to have a highproduct of the carrier electron density and carrier electron mobility.

However, focusing on the heat ray shielding function, it has been foundthat as the carrier electron density is increased higher, the plasmafrequency is shifted to the shorter wavelength side and thus the heatray shielding function can be improved more. On the other hand, as thecarrier electron mobility is lowered more, the absorption coefficient ofIR rays is increased more and thus the heat ray shielding function canbe improved more. That is, either the carrier electron density isincreased or the carrier electron mobility is lowered, so that the heatray shielding function so efficient as to satisfy Tv/Ts≧1.0 can beobtained.

Accordingly, it has been found that an extremely high heat ray shieldingfunction can be accomplished by increasing the carrier electron densityand lowering the carrier electron mobility.

Practically, with respect to the gallium containing zinc oxide of thepresent invention, the carrier electron density n_(e) and the carrierelectron mobility μ are preferable to satisfy the inequality: μ≦3.75n_(e)×10⁻²⁰.

If μ≦3.75 n_(e)×10⁻²⁰ is satisfied, an extremely high heat ray shieldingfunction can be accomplished.

The gallium containing zinc oxide of the present invention is preferableto further contain an element having a covalent bond radius differentfrom that of zinc atom in the same content or lower than the content ofthe gallium.

Addition of the above-mentioned element having a covalent bond radiusdifferent from that of zinc atom causes strains in the shape of thegallium containing zinc oxide crystal and as a result, the carrierelectrons mobility can be decreased to a preferable range and additionof element having a covalent bond radius different from that of zincatom in the same content or lower than the content of the galliumprovides a further improved heat ray shielding function to the galliumcontaining zinc oxide of the present invention without interfering theabove-mentioned properties of gallium.

The above-mentioned element having a covalent bond radius different fromthat of zinc atom is not particularly limited and elements having atetra-coordination ion radius in the range of 0.4 to 0.95 nm exceptgallium are preferable.

If the ion radius is smaller than 0.4 nm, the effect of causing thestains in the crystal is too slight to obtain the heat ray shieldingfunction in some cases and if it exceeds 0.95 nm, the crystal is toomuch strained the stability of the crystal and the reproducibility inproduction become scant owing to excess strains of the crystal.Practically, indium, silicon, thallium, tin, lead, cadmium, cobalt,iron, molybdenum, manganese and the like can be exemplified.

Herein, the ion radius in this description is based on the document:Acta Crystallogr., A 32, 751 (1976) proposed by Shannon.

In this connection, in the case of a cation, the numerical valueobtained by adding 0.14 to the ion radius according to the definition byShannon is defined as the commonly employed ion radium (there aredescriptions in e.g. Introduction to Solid Chemistry written by L.SMART, E. MOORE (Kagaku-Dojin Publishing Company, INC.), InorganicChemistry, second edition written by Gary L Misees slek, Dodald A Tarr(PHIPE PRENTICE HALL Inc.).

Accordingly, the ion radius in the present invention is defined as thenumerical value obtained by adding 0.14 to the ion radius according tothe definition by Shannon.

The above-mentioned element having a covalent bond radius different fromthat of zinc atom is particularly preferable to be an element of GroupXIII elements or Group XIV elements except gallium. Practical examplesof the element is indium and thallium of the Group XIII elements and tinand lead of Group XIV elements.

Also, the above-mentioned element having a covalent bond radiusdifferent from that of zinc atom is preferably fluorine element orchlorine element besides the above-mentioned exemplified elements.

Addition of the above-mentioned fluorine element or chlorine elementprovides a high heat ray shielding function to the gallium containingzinc oxide of the present invention.

Regarding the obtained gallium containing zinc oxide, the heat rayshielding function may be improved by increasing the quantity of theoxygen deficiency by further heating in the reducing gas atmosphere.

However, if the quantity of the oxygen deficiency is increased to anexcess extent, the moisture resistance is deteriorated, physicalproperty alteration with the lapse of time become too significant orlocal luster is caused and crystal structure of zinc oxide cannot bemaintained because of zinc precipitation and therefore, addition has tobe carried out carefully.

Since the gallium containing zinc oxide of the present invention has ahigh solar transmission and the heat ray shielding function, it can beused as vehicular window glass by being formed in a thin film.

A production method of gallium containing zinc oxide and a galliumcontaining zinc oxide thin film of the present invention is preferablyan ion plating method using an ion plating apparatus as described below.

The present invention also includes the gallium containing zinc oxidethin film produced from the gallium containing zinc oxide of the presentinvention.

The gallium containing zinc oxide thin film of the present invention isproduced of the gallium containing zinc oxide of the present inventionand has a film thickness of 5 μm or thinner, the solar transmission Tsand the visible light transmission Tv satisfying Ts≦1.4 Tv−39.

If the above-mentioned correlation is not satisfied, that is Ts>1.4Tv−39, it results in the following consequence: even if the heat rayshielding function is sufficient, in the case the thin film is used forwindow glass for vehicles, proper visible light transmission canobtained but the heat ray shielding function cannot sufficiently beexhibited to a required extent.

Also, if the film thickness is in the range of 30 to 350 nm, Ts≦1.4Tv−44 is preferable and Ts≦1.4 Tv−54 is more preferable. If the filmthickness is in the range of 350 to 5000 nm, Ts≦1.4 Tv−54 is preferableand Ts≦1.4 Tv−63 is more preferable.

The film thickness of the gallium containing zinc oxide thin film of thepresent invention is preferably in the range of 350 to 5000 nm, morepreferably in the range of 100 to 5000 nm, furthermore preferably in therange of 200 to 2000 nm, and even more preferably in the range of 400 to2000 nm, however since the gallium containing zinc oxide thin film ofthe present invention can sufficiently exhibit the heat ray shieldingfunction even if being thin, the thickness may be 30 to 350 nm, 100 to300 nm, 150 to 300 nm, 100 to 200 nm, 200 to 300 nm or the like.

The gallium containing zinc oxide thin film of the present invention ispreferable to have a film thickness of 5000 nm or thinner, and thevisible light transmission Tv of 70% or higher and/or the transmissionof 70% or higher for light rays with wavelength of 500 nm.

If the film thickness exceeds 5000 nm, in the case the galliumcontaining zinc oxide thin film of the present invention is used forwindow glass for vehicles, a desirable visible light transmission forthe window glass for vehicles cannot be obtained and therefore goodvisibility cannot be obtained in some cases.

The Tv is more preferably 75% or higher and/or the transmission forlight rays with wavelength of 500 nm is more preferably 75% or higher,and the Tv is furthermore preferably 80% or higher and/or thetransmission for light rays with wavelength of 500 nm is furthermorepreferably 80% or higher.

The gallium containing zinc oxide thin film of the present invention ispreferable to have the transmission of 88% or lower for light rays withwavelength of 750 nm. If the transmission for light rays with wavelengthof 750 nm exceeds 88%, the sufficient heat ray shielding function cannotbe obtained in some cases.

The transmission for light rays with wavelength of 750 nm is morepreferably 75% or lower, furthermore preferably 65% or lower, and evenmore preferably 55% or lower.

The gallium containing zinc oxide thin film of the present invention ispreferable to have the transmission of 80% or lower for light rays withwavelength of 1000 nm. If the transmission for light rays withwavelength of 1000 nm exceeds 80%, the sufficient heat ray shieldingfunction cannot be obtained in some cases.

The transmission for light rays with wavelength of 1000 nm is morepreferably 60% or lower, furthermore preferably 50% or lower, and evenmore preferably 40% or lower.

The gallium containing zinc oxide thin film of the present invention ispreferable to have the transmission of 65% or lower for light rays withwavelength of 1200 nm. If the transmission for light rays withwavelength of 1200 nm exceeds 65%, the sufficient heat ray shieldingfunction cannot be obtained in some cases.

The transmission for light rays with wavelength of 1200 nm is morepreferably 35% or lower, furthermore preferably 25% or lower, and evenmore preferably 15% or lower.

The gallium containing zinc oxide thin film of the present invention ispreferable to have the transmission of 40% or lower for light rays withwavelength of 1500 nm. The light rays with wavelength of around 1500 nmincluded in the sunrays are highly effective to give scorchingstimulation to the skin. If the transmission for light rays with thewavelength is suppressed, the stimulation to the skin by the heat beamcan be moderated. Accordingly, if the transmission for light rays withwavelength of 1500 nm is 40% or lower, the stimulation by the heat raycan sufficiently be lessened.

The transmission for light rays with wavelength of 1500 nm is morepreferably 15% or lower, furthermore preferably 10% or lower, and evenmore preferably 5% or lower.

The present invention also include a gallium containing zinc oxide thinfilm which satisfies Y≧0.4 X+1.06 in the case the film thickness is 400nm or thicker and Y≧0.2 X+0.98 in the case the film thickness is 300 nmor thinner, in the case X is the value of (carrier electrondensity×10⁻²⁰/carrier electron mobility) and Y is the value of Tv/Ts.

That the thin film satisfies Y≧0.4 X+1.06 in the case the film thicknessis 400 nm or thicker means if the carrier electron density is heightenedand the carrier electron mobility is lowered, it is made possible toobtain a gallium containing zinc oxide thin film with an extremely highheat ray shielding function giving a high visible light transmission Tvwhile keeping a high solar transmission Ts.

On the other hand, that the thin film satisfies Y≧0.2 X+0.98 in the casethe film thickness is 300 nm or thinner means if the carrier electrondensity is heightened and the carrier electron mobility is lowered, itis made possible to obtain a gallium containing zinc oxide thin filmwith a very high heat ray shielding function giving a high visible lighttransmission Tv while keeping a high solar transmission Ts.

Further, it is made clear that the gallium containing zinc oxidesatisfying Y≧0.4 X+1.06, which means the extremely high heat rayshielding function can be attained in the case the film thickness is 400nm or thicker, can be produced stably. Accordingly, if the filmthickness is 400 nm or thicker, the extremely high heat ray shieldingfunction can be obtained.

The production method of the above-mentioned gallium containing zincoxide thin film is preferably an ion plating method using an ion platingapparatus (hereinafter, also referred to as reactive plasma depositionapparatus) by RPD (Reactive Plasma Deposition) method.

FIG. 1 is a schematic drawing of one embodiment of the reactive plasmadeposition apparatus.

The RPD method is a method for forming a film of the respectiveparticles of zinc oxide to the substrate 1 put on the opposite to thehearth 2 by setting zinc oxide containing a dopant (gallium) as a filmformation material in a hearth 2 as an electrode part installed in afilm formation chamber, heating the substrate 1 to about 200° C.,keeping the temperature for a while, radiating plasma using argon or thelike to the zinc oxide from a plasma beam generator 3 for heating thezinc oxide, evenly evaporating the surface of the zinc oxide as atarget.

According to the method, the thin film composition of the film formed onthe substrate can be kept even from an initial period of the thin filmformation to the final period of the thin film formation withoutalteration of the composition in the film during the film formation togive a thin film with a uniform composition. Unlike a magnetronsputtering method, the substrate temperature is scarcely increasedduring the film formation, so that an extremely even thin film can beobtained if a sputtering raw material with high purity is used.

In a production method of a gallium containing zinc oxide thin film byconventional ion plating method, it is common to enclose a largequantity of oxygen gas through a ventilation hole 4 for assistingoxidation during the film formation and evacuate the gas through anevacuation hole 5.

However, to produce the gallium containing zinc oxide thin film of thepresent invention, it is found that oxygen flow amount is rather loweredso as to draw a higher heat ray shielding function. Further,surprisingly, it is found that particularly in the case the galliumcontent is in the range of 0.25 to 5.5% by weight, it is no at all needto introduce oxygen gas.

Practically, in the case, for example, a plasma plating system by theRPD method manufactured by Sumitomo Heavy Industries, Ltd., the oxygenflow amount is adjusted by changing the pressure of a partial pressurepump to lower the oxygen flow amount 13 sccm or lower, and the carrierelectron density and the carrier electron mobility can thus be kept inthe above-mentioned ranges.

However, if the gallium content exceeds 5.5% by weight, it is preferableto assist oxidation by oxygen gas. Without oxygen gas, the film qualitycannot be stabilized and it sometimes becomes difficult to obtain adesired gallium containing zinc oxide thin film. That is, it sometimesbecomes difficult to obtain an even gallium containing zinc oxide thinfilm at a high reproducibility.

The present invention also include a gallium containing zinc oxide thinfilm which is produced under a condition of a gallium content of in therange of 0.25 to 5.5% by weight and oxygen flow amount in the range of 0to 10 sccm, the solar transmission Ts and the visible light transmissionTv satisfying Ts≦1.4 Tv−39.

And the present invention also include a gallium containing zinc oxidethin film which is produced under a condition of a gallium content of inthe range of 5.5 to 25% by weight and oxygen flow amount exceeding 0sccm and not higher than 13 sccm, the solar transmission Ts and thevisible light transmission Tv satisfying Ts≦1.4 Tv−39.

An even gallium containing zinc oxide thin film can be obtained at ahigh reproducibility and an excellent heat ray shielding function can beobtained by satisfying the above-mentioned relation.

FIG. 2 shows the correlation of the visible light transmission Tv andthe solar transmission Ts of gallium containing zinc oxide thin films ofthe present invention having a film thickness of in the range of 100 to300 nm and aluminum containing zinc oxide thin films with a filmthickness of in the range of 100 to 300 nm described in Japanese KokaiPublication Hei-1-201021.

In the case of approximately same film thickness, the gallium containingzinc oxide thin films of the present invention are found havingsufficient transparency to use them for glass for vehicles althoughdecreased in the visible light transmission as compared with theconventional aluminum containing zinc oxide thin films, and the galliumcontaining zinc oxide thin films also are found having a remarkablyimproved heat ray shielding function as compared with the conventionalaluminum containing zinc oxide thin films.

FIG. 3 shows the correlation of the visible light transmission Tv andthe solar transmission Ts of gallium containing zinc oxide thin films ofthe present invention having a film thickness in the range of 527 to 705nm, an aluminum containing zinc oxide thin films with a film thicknessof 577.2 nm described in Japanese Kokai Publication Hei-1-201021, and analuminum containing zinc oxide thin films with a film thickness of 2000nm described in Japanese Kokai Publication Hei-6-293956.

Similarly to FIG. 2, in the case of approximately same film thickness,the gallium containing zinc oxide thin films of the present inventionare found having sufficient transparency to use them for glass forvehicles although decreased in the visible light transmission ascompared with the conventional aluminum containing zinc oxide thin filmdescribed in Japanese Kokai Publication Hei-1-201021.

Also, since the visible light transmission Tv and the solar transmissionTs of the gallium containing zinc oxide thin films of the presentinvention having a film thickness in the range of 527 to 705 nm andapproximately same as those of the conventional aluminum containing zincoxide thin films with a film thickness of 2000 nm, the galliumcontaining zinc oxide thin films of the present invention are foundhaving a sufficient heat ray shielding function with no need to have afilm thickness so thick as that of the conventional aluminum containingzinc oxide thin film.

EFFECT OF THE INVENTION

The present invention can provide a gallium containing zinc oxide withan improved heat ray shielding function while keeping high transparencyto visible light rays.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in details withreference to examples, however the present invention is not limited tothese examples.

In an ion plating apparatus by a RPD method employed in the followingexperiments, argon was used for plasma gas as the operation transmissionother than oxygen partial pressure and while the argon flow amount waskept constant at 30 sccm, the oxygen flow amount was changed to changethe oxygen partial pressure. The plasma radiation current was kept at100 A. The film thickness of zinc oxide films was adjusted to be in therange of 100 nm to 3000 nm (measured by a Surface Profiler). Glasssubstrates (NA 35, alkali-free glass, TFT-grade one side-polishedproduct, manufactured by NH Techno glass Co., Ltd., 120 mm×120 mm×0.7mm) were used as the materials to be coated with the zinc oxide films.Washing of the glass substrates was carried out as follows: 1: rubbingwith a detergent, 2: washing for 10 minutes with flowing water, 3:ultrasonic washing for 5 minutes with pure water (repeated twice), 4:ultrasonic washing for 5 minutes with isopropyl alcohol, and 5: blowingwith nitrogen gas in this order. The temperature of the glass substrateswas adjusted to be at 200° C. The oxygen gas for assisting oxidationduring the film formation was changed between 0 sccm and 20 sccm.

EXPERIMENT EXAMPLES 1 TO 10 AND EXPERIMENT EXAMPLES 13 TO 19

Gallium containing zinc oxide thin films with compositions shown inTable 1 were produced by using the ion plating apparatus shown inFIG. 1. The film thicknesses were as shown in Table 1.

EXPERIMENT EXAMPLES 11 AND 12 AND EXPERIMENT EXAMPLES 20 TO 21

Gallium containing zinc oxide thin films with compositions shown inTable 1 which further contained dopants with the compositions shown inTable 1 were produced by using the ion plating apparatus shown inFIG. 1. The film thicknesses were as shown in Table 1.

<Evaluation>

The gallium containing zinc oxide thin films obtained in Experimentexamples 1 to 21 were subjected to the following evaluations. Theresults are shown in Table 1.

(1) Measurement of Gallium Content (Gallium Content in Raw Materials andFilms)

In addition to the contents (% by weight) of gallium in zinc oxide rawmaterials, the contents of gallium in the formed gallium containing zincoxide thin films were measured by XRF (X-ray Fluorescence analysis)-FP(Fundamental Parameter) method. The measurement was carried out usingthe following apparatus under the following conditions.

PW2400 manufactured by Spectris Co., Ltd.

Sample diameter: 10 mmφ

FP processing soft: FP-MULTI

(2) Measurement of Carrier Electron Density and Carrier ElectronMobility

The carrier electron density and the carrier electron mobility weremeasured by hole effect measurement. The measurement was carried outusing the following apparatus under the following conditions.

HL 5570PC, manufactured by ACCENT OPTICAL TECHNOLOGIES Co., Ltd.

Sample size: 10 mm square

(3) Measurement of Transmission

Using a spectrophotometer (U-4000, manufactured by Hitachi Ltd.), thetransmission at 500 nm, 750 nm, 1000 nm, 1200 nm, and 1500 nm in thenear IR region was measured. Also, the transmission for light rays withwavelength of in the range of 300 to 2100 nm was measured according toJIS R 3106 and from these measurement results, the visible lighttransmission Tv and the solar transmission Ts were calculated.

TABLE 1 content of simultaneously gallium added dopant by carriercontent gallium XRF-FP oxygen carrier electron in raw content by(10²⁰/cm³). film flow electron mobility material XRF-FP element shownthickness amount density n_(e) μ n_(e) × 10⁻¹⁰/ (wt. %) (10²⁰/cm³) inparenthesis (nm) (sccm) (10²⁰/cm³) (cm²/Vs) μ Experiment 3 9 0 200 5 7.727 0.29 example 1 Experiment 3 9.3 0 200 5 8.8 24.5 0.36 example 2Experiment 3 9.4 0 500 5 9.1 17 0.54 example 3 Experiment 4 12 0 500 511.8 21 0.56 example 4 Experiment 5 15 0 500 5 13 20 0.65 example 5Experiment 7 21.5 0 200 10 20.6 6 3.43 example 6 Experiment 7 20.5 0 20010 19 9.2 2.07 example 7 Experiment 10 30.5 0 200 10 27.2 1.9 14.32example 8 Experiment 10 30 0 200 10 26.5 2.6 10.19 example 9 Experiment20 32 0 200 10 27.1 2.1 12.90 example 10 Experiment 10 29 9 (Si) 200 1025.5 1 25.50 example 11 Experiment 10 28.5 9.5 (Si) 200 10 25.8 0.928.67 example 12 Experiment 5 15 0 2000 5 13 12 1.08 example 13Experiment 5 15 0 3000 5 12.5 10 1.25 example 14 Experiment 5 15 0 400 513 20.5 0.63 example 15 Experiment 5 15 0 600 5 13 21.5 0.60 example 16Experiment 10 30 0 1000 10 20.5 9.1 2.25 example 17 Experiment 10 30.5 01500 10 15.5 12 1.29 example 18 Experiment 10 30 0 2000 10 20.5 4.6 4.46example 19 Experiment 10 29 9 (In) 200 10 22.5 0.5 45.00 example 20Experiment 10 28.5 9.5 (Al) 200 10 26.5 0.7 37.66 example 21 trans-trans- trans- trans- trans- visible light solar mission mission missionmission mission transmission transmission (500 nm) (750 nm) (1000 nm)(1200 nm) (1500 nm) Tv (%) Ts (%) Tv/Ts Experiment 96 94 90 80 50 96 801.20 example 1 Experiment 96 94 90 65 39.5 96 80 1.20 example 2Experiment 84.6 81.2 57.9 27.3 3 84.5 62.6 1.35 example 3 Experiment83.1 80.4 43 12.5 0.8 83.6 58.7 1.42 example 4 Experiment 82.9 80.4 39.621 0.8 83.1 57.8 1.44 example 5 Experiment 83 80 65 22 9 78 51 1.53example 6 Experiment 90 87 73 25 10 85 64 1.33 example 7 Experiment 8279 64 15 3 77 47 1.64 example 8 Experiment 85 82 66 18 4 80 51 1.57example 9 Experiment 83 80 59 8 3.5 78 49 1.59 example 10 Experiment 8077 62 6 2.5 75 43 1.74 example 11 Experiment 78 75 61.3 5.7 2.2 73 401.83 example 12 Experiment 82 78 60 34.5 9.5 83.3 61.9 1.35 example 13Experiment 78 65 50 20 8.5 78.5 55.6 1.41 example 14 Experiment 83.381.2 52.4 10.5 2 83.6 61 1.37 example 15 Experiment 82.3 78 31.5 6.5 0.382.8 55.5 1.49 example 16 Experiment 78.5 65 50.5 20 9 78.3 56.2 1.39example 17 Experiment 76 60 46 17 7 76 53 1.43 example 18 Experiment77.7 56.6 20.5 9.8 5.6 77.8 45.8 1.70 example 19 Experiment 80 77 62 62.5 75 43 1.74 example 20 Experiment 78 75 61.3 5.7 2.2 73 40 1.83example 21

EXPERIMENT EXAMPLES 22 TO 116

Gallium containing zinc oxide thin films with compositions shown inTables 2 to 6 were produced by using the ion plating apparatus shown inFIG. 1. The film thicknesses were as shown in Tables 2 to 6.

<Evaluation>

The gallium containing zinc oxide thin films obtained in Experimentexamples 22 to 116 were subjected to the following evaluations. Theresults are shown in Tables 2 to 6 and FIGS. 4 to 10.

(1) Measurement of Gallium Content (Gallium Content in Raw Materials andFilms)

In addition to the contents (% by weight) of gallium in zinc oxide rawmaterials, the contents of gallium in the formed gallium containing zincoxide thin films were measured by XRF (X-ray Fluorescence analysis)-FP(Fundamental Parameter) method. The measurement was carried out usingthe following apparatus under the following conditions.

PW2400 manufactured by Spectris Co., Ltd.

Sample diameter: 10 mmφ

FP processing soft: FP-MULTI

(2) Measurement of Carrier Electron Density and Carrier ElectronMobility

The carrier electron density and the carrier electron mobility weremeasured by hole effect measurement. The measurement was carried outusing the following apparatus under the following conditions.

HL 5570PC, manufactured by ACCENT OPTICAL TECHNOLOGIES Co., Ltd.

Sample size: 10 mm square

(3) Measurement of Transmission 1

Using a spectrophotometer (U-4000, manufactured by Hitachi Ltd.), thetransmission at 500 nm, 750 nm, 1000 nm, 1200 nm, and 1500 nm in thenear IR region was measured. Also, the transmission for light rays withwavelength of in the range of 300 to 2100 nm was measured according toJIS R 3106 and from these measurement results, the visible lighttransmission Tv and the solar transmission Ts were calculated. Further,among the thin films of Experiment examples 22 to 111, those having thecarrier electron density of 1×10²¹/cm³ or higher were marked with ∘;those having the carrier electron density of 7×10²⁰/cm³ or higher andlower than 1×10²¹/cm³ were marked with ▪; those having the carrierelectron density of 2×10²⁰/cm³ or higher and lower than 7×10²⁰/cm³ weremarked with Δ; and those having the carrier electron density of lowerthan 2×10²⁰/cm³ were marked with x and the correlation of the visiblelight transmission Tv and the solar transmission Ts is shown in FIG. 4and also the correlation of the oxygen flow amount and the carrierelectron density is shown in FIG. 5.

Also, the correlation of the visible light transmission Tv and the solartransmission Ts of those having the gallium content in the range of 3 to11% by weight and the oxygen flow amount in the range of 0 to 10 sccmamong the gallium containing zinc oxide thin films of Experimentexamples 22 to 111 is shown in FIG. 6 and the correlation of the carrierelectron density n_(e) and the carrier mobility μ is shown in FIG. 7.

Further, the relation of (carrier electron density×10⁻²⁰/carrierelectron mobility) with Tv/Ts for the gallium containing zinc oxide thinfilms of Experiment examples 1 to 116 is shown in FIG. 8.

(4) Measurement of Transmission 2

With respect to the gallium containing zinc oxide thin films ofExperiment examples 22 to 111, the transmission for the light rays withwavelength of in the range of 300 to 2500 nm was measured by aspectrophotometer (U-4000, manufactured by Hitachi Ltd.). FIG. 9 showsthe correlation of the wavelength and transmission of those obtainedunder condition of oxygen flow amount of 5 sccm among the thin films andFIG. 10 shows the correlation of those obtained under condition ofoxygen flow amount of 10 sccm.

TABLE 2 gallium content in oxygen carrier carrier raw film flow electronelectron solar visible light material thickness amount density n_(e)mobility μ n_(e) × 10⁻²⁰/ transmission transmission (wt. %) (nm) (sccm)(10²⁰/cm³) (cm²/Vs) μ Ts (%) Tv (%) Experiment 1 120 0 4.933 20.7 0.2479.5 81.5 example 22 Experiment 1 129 2.5 5.266 22.2 0.24 81.7 85.9example 23 Experiment 1 140 5 5.033 24.8 0.20 81.8 87.4 example 24Experiment 1 179 7.5 3.969 28.3 0.14 82.5 87.1 example 25 Experiment 1296 10 3.174 33.4 0.10 83.2 80.7 example 26 Experiment 1 199 12.5 3.13336.4 0.09 84.0 83.2 example 27 Experiment 1 213 15 2.602 35.2 0.07 84.681.5 example 28 Experiment 1 219 17.5 1.755 24.1 0.07 84.8 80.4 example29 Experiment 1 233 20 1.246 14.7 0.08 84.5 81.4 example 30 Experiment 2149 0 8.456 21.7 0.39 77.5 86.0 example 31 Experiment 2 148 2.5 8.20223.1 0.36 78.8 86.6 example 32 Experiment 2 212 5 7.183 28.6 0.25 77.883.9 example 33 Experiment 2 204 7.5 7.641 30.0 0.25 78.3 82.4 example34 Experiment 2 236 10 6.446 32.5 0.20 79.0 82.0 example 35 Experiment 2251 12.5 5.511 33.2 0.17 79.9 82.7 example 36 Experiment 2 256 15 4.79431.7 0.15 80.6 83.5 example 37 Experiment 2 283 17.5 3.236 26.0 0.1281.6 83.2 example 38 Experiment 2 263 20 2.218 20.1 0.11 83.8 84.8example 39 trans- trans- trans- trans- trans- mission mission missionmission mission Tv/Ts 1.4Tv-54 1.4Tv-44 (500 nm) (750 nm) (1000 nm)(1200 nm) (1500 nm) Experiment 1.03 60.1 70.1 82.8 81.0 84.2 81.7 70.6example 22 Experiment 1.05 66.3 76.3 87.4 83.8 85.8 81.9 69.1 example 23Experiment 1.07 68.4 78.4 86.8 84.2 85.5 82.9 70.7 example 24 Experiment1.06 67.9 77.9 81.9 87.0 85.6 84.0 73.7 example 25 Experiment 0.97 59.069.0 76.3 90.6 86.1 85.3 79.6 example 26 Experiment 0.99 62.5 72.5 77.590.2 86.4 86.2 80.6 example 27 Experiment 0.96 60.1 70.1 77.9 91.7 87.486.7 82.7 example 28 Experiment 0.95 58.6 68.6 80.8 92.0 88.3 86.5 84.5example 29 Experiment 0.96 60.0 70.0 86.7 90.0 89.4 86.1 84.9 example 30Experiment 1.11 66.4 76.4 85.1 84.8 81.3 68.5 52.7 example 31 Experiment1.10 67.2 77.2 87.1 85.4 82.5 70.2 55.3 example 32 Experiment 1.08 63.573.5 79.0 88.1 83.0 69.8 47.6 example 33 Experiment 1.05 61.4 71.4 79.688.9 83.9 72.2 47.7 example 34 Experiment 1.04 60.8 70.8 82.7 89.1 84.875.6 51.1 example 35 Experiment 1.04 61.8 71.8 86.6 88.5 85.7 79.4 57.7example 36 Experiment 1.04 62.9 72.9 88.7 88.4 88.7 81.4 61.6 example 37Experiment 1.02 62.5 72.5 88.8 87.8 87.8 84.2 70.3 example 38 Experiment1.01 64.7 74.7 90.8 88.2 89.7 86.6 79.8 example 39

TABLE 3 gallium content in oxygen carrier carrier raw film flow electronelectron solar visible light material thickness amount density n_(e)mobility μ n_(e) × 10⁻²⁰/ transmission transmission (wt. %) (nm) (sccm)(10²⁰/cm³) (cm²/Vs) μ Ts (%) Tv (%) Experiment 3 193 0 10.48 24.2 0.4373.8 85.9 example 40 Experiment 3 199 2.5 10.46 25.3 0.41 74.1 85.4example 41 Experiment 3 206 5 10.02 25.9 0.39 74.1 84.5 example 42Experiment 3 225 7.5 9.344 27.9 0.33 74.4 83.0 example 43 Experiment 3240 10 8.343 29.9 0.28 75.1 82.7 example 44 Experiment 3 248 12.5 6.8529.2 0.23 76.6 83.4 example 45 Experiment 3 263 15 5.365 28.5 0.19 78.583.5 example 46 Experiment 3 255 17.5 4.060 26.7 0.15 81.2 84.3 example47 Experiment 3 270 20 2.120 23.5 0.09 83.3 84.8 example 48 Experiment 4178 0 11.84 22.7 0.52 73.9 87.6 example 49 Experiment 4 179 2.5 11.7123.9 0.49 73.7 87.1 example 50 Experiment 4 216 5 10.26 25.0 0.41 73.585.7 example 51 Experiment 4 233 7.5 9.714 26.5 0.37 73.2 84.2 example52 Experiment 4 236 10 9.691 28.4 0.34 74.0 83.6 example 53 Experiment 4244 12.5 7.580 29.2 0.26 75.9 83.0 example 54 Experiment 4 273 15 5.82931.2 0.19 77.7 85.1 example 55 Experiment 4 274 17.5 3.430 28.3 0.1281.6 84.6 example 56 Experiment 4 278 20 2.851 27.0 0.11 82.7 85.1example 57 trans- trans- trans- trans- trans- mission mission missionmission mission Tv/Ts 1.4Tv-54 1.4Tv-44 (500 nm) (750 nm) (1000 nm)(1200 nm) (1500 nm) Experiment 1.16 66.3 76.3 81.9 86.6 75.2 55.0 32.3example 40 Experiment 1.15 65.6 75.6 81.1 86.9 76.0 55.6 32.7 example 41Experiment 1.14 64.3 74.3 80.1 87.0 76.8 56.6 32.8 example 42 Experiment1.12 62.2 72.2 80.5 87.4 78.3 58.2 31.6 example 43 Experiment 1.10 61.871.8 84.0 87.3 79.9 62.5 33.5 example 44 Experiment 1.09 62.8 72.8 87.587.1 82.1 70.0 40.5 example 45 Experiment 1.06 62.9 72.9 88.0 88.0 84.875.9 48.7 example 46 Experiment 1.04 64.0 74.0 89.8 87.6 87.6 83.6 67.2example 47 Experiment 1.02 64.7 74.7 90.2 87.3 89.4 86.5 79.5 example 48Experiment 1.19 68.6 78.6 85.0 87.1 73.3 52.9 30.0 example 49 Experiment1.18 67.9 77.9 84.0 87.1 73.7 52.6 29.3 example 50 Experiment 1.17 66.076.0 82.0 87.1 74.7 52.4 27.8 example 51 Experiment 1.15 63.9 73.9 81.486.9 75.4 52.3 26.4 example 52 Experiment 1.13 63.0 73.0 82.9 86.7 78.457.5 32.0 example 53 Experiment 1.09 62.2 72.2 87.0 86.3 81.3 69.3 39.9example 54 Experiment 1.10 65.1 75.1 89.6 85.8 83.6 76.2 49.1 example 55Experiment 1.04 64.4 74.4 90.1 87.0 87.9 84.6 71.0 example 56 Experiment1.03 65.1 75.1 90.1 87.0 89.2 86.1 78.8 example 57

TABLE 4 gallium content in oxygen carrier carrier raw film flow electronelectron solar visible light material thickness amount density n_(e)mobility μ n_(e) × 10⁻²⁰/ transmission transmission (wt. %) (nm) (sccm)(10²⁰/cm³) (cm²/Vs) μ Ts (%) Tv (%) Experiment 5 171 0 12.06 19.2 0.6374.0 87.3 example 58 Experiment 5 183 2.5 11.06 20.9 0.53 74.2 87.2example 59 Experiment s 203 5 11.12 20.5 0.54 73.8 86.5 example 60Experiment 5 219 7.5 10.64 24.1 0.44 73.2 84.3 example 61 Experiment 5255 10 8.802 27.4 0.32 73.3 83.0 example 62 Experiment 5 260 12.5 7.39729.1 0.25 74.9 83.1 example 63 Experiment 5 264 15 5.628 28.5 0.20 78.084.3 example 64 Experiment 5 250 17.5 4.055 25.9 0.16 80.9 85.0 example65 Experiment 5 262 20 2.195 22.2 0.10 83.4 86.0 example 66 Experiment 6135 0 7.267 11.2 0.65 80.2 85.9 example 67 Experiment 6 176 2.5 9.55316.7 0.57 75.5 86.8 example 68 Experiment 6 168 5 9.444 17.6 0.54 74.685.8 example 69 Experiment 6 209 7.5 9.351 18.5 0.51 74.3 84.9 example70 Experiment 6 239 10 9.239 23.6 0.39 73.5 82.7 example 71 Experiment 6248 12.5 8.103 25.1 0.32 74.0 82.1 example 72 Experiment 6 265 15 5.73924.9 0.23 76.7 83.8 example 73 Experiment 6 270 17.5 4.187 24.7 0.1779.9 85.2 example 74 Experiment 6 274 20 2.720 22.9 0.12 81.9 86.2example 75 trans- trans- trans- trans- trans- mission mission missionmission mission Tv/Ts 1.4Tv-54 1.4Tv-44 (500 nm) (750 nm) (1000 nm)(1200 nm) (1500 nm) Experiment 1.18 68.2 78.2 85.0 86.6 74.8 52.0 31.0example 58 Experiment 1.18 68.1 78.1 84.7 86.7 75.7 52.9 31.4 example 59Experiment 1.17 67.1 77.1 83.3 86.7 75.6 52.3 29.9 example 60 Experiment1.15 64.0 74.0 81.5 86.4 75.9 52.2 26.5 example 61 Experiment 1.13 62.272.2 83.9 85.9 77.4 56.1 27.3 example 62 Experiment 1.11 62.3 72.3 87.685.2 79.8 67.8 38.6 example 63 Experiment 1.08 64.0 74.0 89.2 86.0 83.777.0 52.5 example 64 Experiment 1.05 65.0 75.0 90.1 86.5 86.8 82.9 67.3example 65 Experiment 1.03 66.4 76.4 90.4 86.1 89.6 86.6 80.4 example 66Experiment 1.07 66.3 76.3 87.5 85.8 82.8 71.3 58.7 example 67 Experiment1.15 67.5 77.5 84.8 85.8 79.3 58.1 39.0 example 68 Experiment 1.15 66.176.1 82.6 85.7 78.5 55.9 35.2 example 69 Experiment 1.14 64.9 74.9 81.386.2 78.2 55.4 32.8 example 70 Experiment 1.13 61.8 71.8 82.4 85.7 77.856.8 29.1 example 71 Experiment 1.11 60.9 70.9 85.6 84.8 78.3 64.2 37.2example 72 Experiment 1.09 63.3 73.3 88.7 85.4 81.7 73.0 48.0 example 73Experiment 1.07 65.3 75.3 89.6 85.3 85.8 81.2 64.6 example 74 Experiment1.05 66.7 78.7 89.1 84.6 88.2 84.7 75.8 example 75

TABLE 5 gallium content in oxygen carrier carrier raw film flow electronelectron solar visible light material thickness amount density n_(e)mobility μ n_(e) × 10⁻²⁰/ transmission transmission (wt. %) (nm) (sccm)(10²⁰/cm³) (cm²/Vs) μ Ts (%) Tv (%) Experiment 7 173 0 6.357 11.1 0.5778.9 88.3 example 76 Experiment 7 168 2.5 7.771 12.3 0.63 77.1 87.4example 77 Experiment 7 176 5 8.473 13.2 0.64 76.3 86.7 example 78Experiment 7 197 7.5 8.798 14.1 0.62 75.2 85.2 example 79 Experiment 7226 10 8.403 18.4 0.46 73.7 82.5 example 80 Experiment 7 257 12.5 7.38122.8 0.32 73.9 82.4 example 81 Experiment 7 272 15 5.612 23.2 0.24 76.183.7 example 82 Experiment 7 265 17.5 4.213 22.4 0.19 79.2 85.3 example83 Experiment 7 283 20 2.543 20.3 0.13 81.8 86.3 example 84 Experiment 8154 0 4.425 10.0 0.44 81.4 89.0 example 85 Experiment 8 159 2.5 5.3099.62 0.55 80.4 89.2 example 86 Experiment 8 173 5 6.770 11.2 0.60 78.287.6 example 87 Experiment 8 202 7.5 7.441 13.9 0.54 75.7 84.8 example88 Experiment 8 218 10 8.009 17.2 0.47 74.1 82.3 example 89 Experiment 8255 12.5 6.945 19.0 0.37 73.6 82.3 example 90 Experiment 8 272 15 5.38819.6 0.27 76.0 84.8 example 91 Experiment 8 274 17.5 3.992 19.1 0.2178.7 86.2 example 92 Experiment 8 275 20 2.488 15.8 0.16 80.1 85.5example 93 trans- trans- trans- trans- trans- mission mission missionmission mission Tv/Ts 1.4Tv-54 1.4Tv-44 (500 nm) (750 nm) (1000 nm)(1200 nm) (1500 nm) Experiment 1.12 69.6 79.6 88.4 85.0 81.8 68.8 53.8example 76 Experiment 1.13 68.4 78.4 85.6 85.2 80.6 63.7 46.8 example 77Experiment 1.14 67.4 77.4 84.0 85.3 80.0 61.8 43.7 example 78 Experiment1.13 65.3 75.3 81.6 85.5 79.1 59.3 38.9 example 79 Experiment 1.12 61.571.5 81.0 85.3 77.6 57.6 33.5 example 80 Experiment 1.12 61.4 71.4 86.184.6 77.6 63.7 37.6 example 81 Experiment 1.10 63.2 73.2 88.6 85.1 80.871.2 46.5 example 82 Experiment 1.08 65.4 75.4 89.5 85.1 85.0 79.4 61.3example 83 Experiment 1.06 66.8 76.8 89.5 84.8 88.3 84.3 74.0 example 84Experiment 1.09 70.6 80.6 90.4 84.5 83.4 77.1 64.8 example 85 Experiment1.11 70.9 80.9 88.9 85.0 82.9 74.4 60.4 example 86 Experiment 1.12 68.678.6 84.9 85.3 81.5 68.7 52.0 example 87 Experiment 1.12 64.7 74.7 81.085.1 79.3 62.4 43.0 example 88 Experiment 1.11 61.2 71.2 80.9 84.9 77.559.4 37.2 example 89 Experiment 1.12 61.2 71.2 86.1 84.2 76.2 61.7 38.8example 90 Experiment 1.12 64.7 74.7 89.1 84.9 80.2 69.9 45.8 example 91Experiment 1.10 66.7 76.7 88.7 84.6 84.5 77.8 58.4 example 92 Experiment1.07 65.7 75.7 90.3 85.8 86.3 80.1 63.9 example 93

TABLE 6 gallium content in oxygen carrier carrier raw film flow electronelectron solar visible light material thickness amount density n_(e)mobility μ n_(e) × 10⁻²⁰/ transmission transmission (wt. %) (nm) (sccm)(10²⁰/cm³) (cm²/Vs) μ Ts (%) Tv (%) Experiment 9 139 0 3.991 8.88 0.4582.4 89.2 example 94 Experiment 9 158 2.5 3.771 9.19 0.41 81.8 89.9example 95 Experiment 9 153 5 4.695 9.14 0.51 81.1 89.5 example 96Experiment 9 173 7.5 5.883 8.66 0.68 80.2 88.4 example 97 Experiment 9209 10 6.259 10.9 0.57 77.4 83.8 example 98 Experiment 9 242 12.5 6.21414.9 0.42 74.8 81.9 example 99 Experiment 9 270 15 5.095 16.4 0.31 75.783.3 example 100 Experiment 9 276 17.5 3.611 17.5 0.21 77.3 85.2 example101 Experiment 9 288 20 2.762 16.1 0.17 79.4 86.7 example 102 Experiment11 147 0 3.076 8.90 0.35 82.8 89.2 example 103 Experiment 11 152 2.52.771 9.17 0.30 82.8 89.3 example 104 Experiment 11 146 5 2.908 9.090.32 82.7 89.8 example 105 Experiment 11 160 7.5 3.220 8.62 0.37 82.390.0 example 106 Experiment 11 193 10 3.318 8.70 0.38 81.3 87.4 example107 Experiment 11 216 12.5 3.371 8.84 0.38 80.4 82.4 example 108Experiment 11 228 15 3.641 10.8 0.34 79.0 80.4 example 109 Experiment 11252 17.5 3.113 9.92 0.31 79.4 81.9 example 110 Experiment 11 256 202.174 8.66 0.25 80.4 82.9 example 111 Experiment 10 546 5 4.9 11 0.4566.2 82.9 example 112 Experiment 8 630 5 6.2 18.5 0.34 61.9 82.7 example113 Experiment 8 527 0 6.1 17 0.36 61.9 82.3 example 114 Experiment 8647 10 5.8 20.1 0.29 64.0 83.2 example 115 Experiment 3 705 10 6.9 33.20.21 68.6 83.5 example 116 trans- trans- trans- trans- trans- missionmission mission mission mission Tv/Ts 1.4Tv-54 1.4Tv-44 (500 nm) (750nm) (1000 nm) (1200 nm) (1500 nm) Experiment 1.08 70.9 80.9 90.8 84.083.5 80.1 70.4 example 94 Experiment 1.10 71.9 81.9 89.7 84.9 83.2 78.867.3 example 95 Experiment 1.10 71.3 81.3 87.4 85.7 82.9 76.9 63.4example 96 Experiment 1.10 69.8 79.8 85.1 86.2 82.5 74.7 59.7 example 97Experiment 1.08 63.3 73.3 79.6 86.7 80.6 68.5 49.7 example 98 Experiment1.09 60.7 70.7 84.8 85.2 77.5 64.3 43.0 example 99 Experiment 1.10 62.672.6 88.1 85.6 79.2 67.3 44.8 example 100 Experiment 1.10 65.3 75.3 89.685.1 82.2 73.1 51.2 example 101 Experiment 1.09 67.4 77.4 88.8 84.4 85.579.1 61.9 example 102 Experiment 1.08 70.9 80.9 90.7 83.6 83.3 81.4 73.6example 103 Experiment 1.08 71.0 81.0 90.8 83.7 83.3 81.5 73.8 example104 Experiment 1.09 71.7 81.7 90.5 84.1 83.1 81.2 73.4 example 105Experiment 1.09 72.0 82.0 88.4 85.4 83.0 80.0 70.5 example 106Experiment 1.08 68.4 78.4 82.4 87.6 82.9 78.3 66.2 example 107Experiment 1.02 61.4 71.4 78.0 89.2 82.9 77.3 63.9 example 108Experiment 1.02 58.6 68.6 82.0 88.4 82.7 75.3 59.5 example 109Experiment 1.03 60.7 70.7 87.3 87.3 84.4 77.3 61.4 example 110Experiment 1.03 62.1 72.1 89.3 86.7 86.3 80.2 67.3 example 111Experiment 1.25 62.1 72.1 87.1 79.2 65.1 40.1 15.9 example 112Experiment 1.34 61.8 71.8 77.4 78.0 59.5 25.1 4.4 example 113 Experiment1.33 61.2 71.2 84.6 75.8 58.9 23.2 7.2 example 114 Experiment 1.30 62.572.5 84.6 81.2 63.8 31.8 5.4 example 115 Experiment 1.22 62.9 72.9 82.182.9 71.9 54.5 7.9 example 116

As being understood from FIG. 4, as the carrier electron density ishigher, the thin films are shown in the more right and lower parts. Thatis, it is made clear that the thin films have a high visible lighttransmission and a low solar transmission. From these results, it ismade clear that as the carrier electron density is higher, a galliumcontaining zinc oxide thin film more excellent in the transparency andthe heat ray shielding function can be obtained.

Further, from FIGS. 9 and 10, it is made clear that the IR reflectionperformance is high in the case the gallium content is in the range of 3to 8% by weight.

INDUSTRIAL APPLICABILITY

The present invention provides a gallium containing zinc oxide with animproved heat ray shielding function while keeping high transparency tovisible light rays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing showing one embodiment of an ion platingapparatus capable of producing a gallium containing zinc oxide thin filmof the present invention.

FIG. 2 is a drawing showing the correlation of the visible lighttransmission and the solar transmission of gallium containing zinc oxidethin films of the present invention and conventional aluminum containingzinc oxide thin films in the case a film thickness is in the range about100 to 300 nm.

FIG. 3 is a drawing showing the correlation of the visible lighttransmission and the solar transmission of gallium containing zinc oxidethin films of the present invention and conventional aluminum containingzinc oxide thin films in the case a film thickness is 500 nm or thicker.

FIG. 4 is a drawing showing the correlation of the visible lighttransmission Tv and the solar transmission Ts of gallium containing zincoxide thin films obtained in Experiment examples 22 to 111.

FIG. 5 is a drawing showing the correlation of the oxygen flow amountand carrier electron density of gallium containing zinc oxide thin filmsobtained in Experiment examples 22 to 111.

FIG. 6 is a drawing showing the correlation of the visible lighttransmission Tv and the solar transmission Ts of gallium containing zincoxide thin films having the gallium content in the range of 3 to 11% byweight and the oxygen flow amount in the range of 0 to 10 sccm among thegallium containing zinc oxide thin film obtained in Experiment examples22 to 111.

FIG. 7 is a drawing showing the correlation of the carrier electrondensity n_(e) and the carrier electron mobility μ of gallium containingzinc oxide thin films having the gallium content in the range of 3 to11% by weight and the oxygen flow amount in the range of 0 to 10 sccmamong the gallium containing zinc oxide thin film obtained in Experimentexamples 22 to 111.

FIG. 8 is a drawing showing the relation of (carrier electrondensity×10⁻²⁰/carrier electron mobility) with Tv/Ts for the galliumcontaining zinc oxide thin films of Experiment examples 1 to 116.

FIG. 9 is a drawing showing the correlation of the wavelength in therange of 300 to 2500 nm and transmission of the gallium containing zincoxide thin films of Experiment examples 22 to 111 obtained undercondition of oxygen flow amount of 5 sccm.

FIG. 10 is a drawing showing the correlation of the wavelength in therange of 300 to 2500 nm and transmission of the gallium containing zincoxide thin films of Experiment examples 22 to 111 obtained undercondition of oxygen flow amount of 10 sccm.

EXPLANATION OF SYMBOLS

-   1 Substrate-   2 Hearth-   3 Plasma beam generator-   4 Ventilation hole-   5 Evacuation hole

1. A gallium containing zinc oxide, which has a heat ray shieldingfunction, a gallium content of in the range of 0.25 to 25% by weight,and a carrier electron density n_(e) of 2×10²⁰/cm³ or higher.
 2. Thegallium containing zinc oxide according to claim 1, wherein a carrierelectron mobility μ is in the range of 0.1 to 40 cm²/Vs.
 3. The galliumcontaining zinc oxide according to claim 1, wherein the carrier electrondensity n_(e) and the carrier electron mobility μ satisfy μ≦3.75n_(e)×10⁻²⁰.
 4. The gallium containing zinc oxide according to claim 1,wherein the carrier electron density n_(e) and the carrier electronmobility μ satisfy 0.2≦(n_(e)×10⁻²⁰/μ) and a solar transmission Ts and avisible light transmission Tv satisfy Tv/Ts≧1.0.
 5. The galliumcontaining zinc oxide according to claim 1, which further contains anelement having a covalent bond radius different from that of zinc atomin the same content or lower than the content of the gallium.
 6. Thegallium containing zinc oxide according to claim 5, wherein the elementhaving a covalent bond radius different from that of zinc atom is anelement having a tetra-coordination ion radius in the range of 0.4 to0.95 nm except gallium.
 7. The gallium containing zinc oxide accordingto claim 5, wherein the element having a covalent bond radius differentfrom that of zinc atom is an element of Group XIII elements or Group XIVelements except gallium.
 8. The gallium containing zinc oxide accordingto claim 5, wherein the element having a covalent bond radius differentfrom that of zinc atom is fluorine element or chlorine element.
 9. Agallium containing zinc oxide thin film, which comprises the galliumcontaining zinc oxide according to claim 1, and has a film thickness of5 μm or thinner, the solar transmission Ts and the visible lighttransmission Tv satisfying Ts≦1.4 Tv−39.
 10. The gallium containing zincoxide thin film according to claim 9, which has a film thickness of 5000nm or thinner, and the visible light transmission Tv of 70% or higherand/or the transmission of 70% or higher for light rays with wavelengthof 500 nm.
 11. The gallium containing zinc oxide thin film according toclaim 9, wherein the solar transmission Ts and the visible lighttransmission Tv satisfy Ts≦1.4 Tv−44 in the case the film thickness isin the range of 30 to 350 nm.
 12. The gallium containing zinc oxide thinfilm according to claim 9, wherein the solar transmission Ts and thevisible light transmission Tv satisfy Ts≦1.4 Tv−54 in the case the filmthickness is in the range of 350 to 5000 mm.
 13. The gallium containingzinc oxide thin film according to claim 9, wherein the transmission forlight rays with wavelength of 750 mm is 88% or lower.
 14. The galliumcontaining zinc oxide thin film according to claim 13, wherein thetransmission for light rays with wavelength of 750 nm is 75% or lower.15. The gallium containing zinc oxide thin film according to claim 9,wherein the transmission for light rays with wavelength of 1000 mm is80% or lower.
 16. The gallium containing zinc oxide thin film accordingto claim 15, wherein the transmission for light rays with wavelength of1000 nm is 60% or lower.
 17. The gallium containing zinc oxide thin filmaccording to claim 9, wherein the transmission for light rays withwavelength of 1200 mm is 65% or lower.
 18. The gallium containing zincoxide thin film according to claim 17, wherein the transmission forlight rays with wavelength of 1200 mm is 35% or lower.
 19. The galliumcontaining zinc oxide thin film according to claim 9, wherein thetransmission for light rays with wavelength of 1500 nm is 40% or lower.20. The gallium containing zinc oxide thin film according to claim 19,wherein the transmission for light rays with wavelength of 1500 mm is15% or lower.
 21. A gallium containing zinc oxide thin film, whichsatisfies Y≧0.4 X+1.06 in the case the film thickness is 400 nm orthicker and Y≧0.2 X+0.98 in the case the film thickness is 300 nm orthinner, in the case X is the value of (carrier electrondensity×10⁻²⁰/carrier electron mobility) and Y is the value of Tv/Ts.22. A gallium containing zinc oxide thin film, which is produced under acondition of a gallium content of in the range of 0.25 to 5.5% by weightand oxygen flow amount in the range of 0 to 10 sccm, the solartransmission Ts and the visible light transmission Tv satisfying Ts≦1.4Tv−39.
 23. A gallium containing zinc oxide thin film, which is producedunder a condition of a gallium content of in the range of 5.5 to 25% byweight and oxygen flow amount exceeding 0 sccm and not higher than 13sccm, the solar transmission Ts and the visible light transmission Tvsatisfying Ts≦1.4 Tv−39.